This disclosure relates generally to liquid and gas flow meters. More particularly, it relates to apparatus and systems for enclosing and protecting transducers and transducer cables that are employed with ultrasonic flow meters.
Hydrocarbons, in both liquid and gas phases, are transported from place to place via pipelines. It is desirable to accurately know the amount of fluid flowing in the stream, particularly when the fluid is changing hands, an event referred to as “custody transfer.” Even where custody transfer is not taking place, measurement accuracy is desirable, and in these situations, ultrasonic flow meters are commonly used.
An ultrasonic flow meter includes a meter body having a central conduit that serves as a fluid passageway for conducting the fluid (liquid or gas) that is being transported in the pipeline, and a pair of flanges for connecting the meter between aligned sections of the pipeline. The body of the flow meter may also be referred to as a spool piece. The ultrasonic flow meter further includes two or more transducer assemblies, each secured in a dedicated port that is formed in the meter body. To measure fluid flow through the meter, the transducer assemblies of the pair are positioned such that the piezoelectric elements of the transducers are adjacent to the inner surface of the spool piece, and such that each transducer faces the other of the pair, which is positioned on the opposite side of the fluid passageway. The transducer assemblies transmit and receive electric signals back-and-forth across the fluid stream.
Each transducer assembly is coupled to a cable that extends from an end connector of the assembly to a remote location, typically an electronics enclosure mounted on or adjacent to the spool piece. The electric signals created by the piezoelectric element of each transducer assembly is carried by the cable to an acquisition circuit board housed within the electronics enclosure, where the signal may be processed and subsequently used to determine useful data including the rate and volume of fluid flow through the flow meter.
If left exposed, the transducers and cables are susceptible to being tampered with and becoming damaged by falling debris, roaming livestock, and vandals. Further, if left unprotected, the cables and transducers are exposed to possible damage during shipping and installation. Further, the cables' insulation can degrade due to constant exposure to weather and sunlight. Consequently, it has been common to employ robust and thus relatively expensive cables in an attempt to resist damage and degradation.
Additionally, attempts have been made to manufacture meter bodies having internal cable passageways that are formed in the walls of the meter body to at least partially cover the cables and provide some degree of protection. In some such products, the ends of the transducer assemblies and portions of the cables are nevertheless still exposed. This arrangement leaves them susceptible to damage or to being tampered with, which may limit the meter's performance in accurately measuring the fluid flow. Other flow meters have included covers intended to completely enclose and protect the transducers and the cables; however, some such covers have had intricate designs that create manufacturing and cable-routing challenges and increased cost.
Other cover designs have required that the transducer assemblies be mounted in deep pockets formed in the meter body so as to limit the extension height of the transducer assemblies above the body's surface. This has required the use of significantly larger meter bodies with thicker walls, larger diameters, and/or greater flange-to-flange length that, in turn, leads to increased weight and cost. Still other covers have been flexible to a degree that creates some difficulty in removing and then properly reinstalling the cover in the field, or have required fasteners that are inconvenient or difficult to install and remove.